1. Field of the Invention
The present invention relates to voice recording and playback devices which include a removable recording medium capable of ready transfer to another similar recording device. More particularly, the present invention pertains to a voice recording and playback device which utilizes a nonvolatile, computer memory chip for record or playback operation for time durations equivalent to cassette tape recorders.
2. Prior Art
The development of devices that are capable of electronic recording and playback using interchangeable recording media has evolved through many technologies. Such electronic reproduction of speech has generally relied on the use of a separate and removable medium, such as a cassette tape, which stores a signal capable of reproduction through some form of amplification system. Such mediums have also included vinyl records and plastic laser disks.
A common characteristic of each of these media is a dependence upon the relative movement of the medium with respect to a sensor to facilitate recovery of the stored signal for reproduction. This requirement for physical movement has necessitated substantial power requirements implemented with hardware components which take up significant space. For example, early records made of vinyl required a turn table and drive mechanism for maintaining a controlled rate of speed. Similarly, cassette recordings utilize a capstan and mechanical drive belt system for maintaining tape speed at a predetermined rate. Laser disks require comparable drive mechanisms to facilitate relative movement of the sensor with respect to the compact disc media.
In addition to mechanical movement of the media, technical difficulties in minimizing background noise associated with sensor pickup continues to test the best minds within the recording industry. For example, stylus design for records has placed primary focus on controlling physical contact of the needle on the vinyl record. Advanced filtering techniques were applied to circuits to reduce resultant noise to a minimum.
Although laser disc technology has overcome many of the physical contact problems, optical reading systems still require conversion of an optical signal to an electrical signal. This conversion process also generates artifact signals which lead to unwanted background noise.
Concurrent with progressive improvement in drive mechanisms has been an increasing consumer interest in reduced size and increased versatility of the recorder itself. As a consequence, pocket sized recorders have become commonplace, whether based on cassette tapes or more current compact disk technology. Nevertheless, the requirement for a drive mechanism continues to limit the extent of size reduction. Indeed, most of the weight and volume of a typical record and playback device comprises the mechanical drive mechanism, associated power supply and control system. Despite decades of technical development, the voice recording and playback industry (dictation devices) continues to depend on the combination of mechanical movement of a removable recorded medium in combination with a pickup sensor.
This almost universal commitment to the use of a moveable medium, such as a cassette tape, continues despite years of experience with fixed memory within computers. For example, it is well known to store virtually all forms of data in either digital or analog format within a computer. This data may even include voice information. Although this information is available for recall, it has not led to the development of a hand-held dictation device which allows convenient use of a removable medium that can be readily inserted into a simple recording device for immediate playback or simple transfer to another similar hand-held recorder.
This use of a fixed memory storage system for voice information has also branched into peripheral components of other equipment, such as telephones. Even when used as part of a telephone answering machine for providing the prerecorded message, common practice is still to apply a cassette recording system for recording incoming messages for storage and playback. Therefore, the basic system either uses a conventional cassette recorder or relies on fixed memory storage which lacks the ability for simple and convenient transfer to other similar units as part of a readily removable, interchangeable, recording medium.
Attempts have also been made to apply fixed memory storage to hand-held devices. Commercial success, however, has been frustrated by the same inadequacies that have sustained allegiance to the standard cassette recorder over the years. For example, Information Storage Devices, Inc., has developed a small, voice record/playback device having nonvolatile memory which is stored in an EEPROM in natural analog form. Unfortunately, the analog storage format has only limited memory capacity, resulting in a short operation span of less than several minutes. Furthermore, the device retains the conventional computer format with no removable and interchangeable recording media comparable to the standard cassette. Without this convenient interchangability aspect, the small device operates with the same limitations of a conventional computer system.